Richness of Spiral Magnetic States in Strontium Ferrite Thin Films

Perovskite strontium ferrite, SrFeO₃, hosts a variety of spiral magnetic phases at low temperature including multi-q states of different proper screw and/or cycloid ordering ^[1]. Among them is a phase believed to support topologically-protected magnetic structures and may explain an observed finite-field anomaly in Hall effect ^[2].<br/>SrFeO₃ is a fascinating material because, unusually, these effects exist despite the centrosymmetry of the crystal structure. Instead of a Dzyaloshinskii-Moriya interaction, the helimagnetism has been suggested to arise due to an interplay of electronic interactions ^[3].<br/>We have optimized the growth and stability of epitaxial thin films of SrFeO₃ grown by pulsed laser deposition. Then, using resonant soft x-ray scattering, we study how these complex magnetic orderings depend on the biaxial strain state, which potentially influences the electronic structure.<br/> <br/>[1] Ishiwata, S. <i>et al.</i> Versatile helimagnetic phases under magnetic fields in cubic perovskite SrFeO₃, <i>Phys. Rev. B </i> <b>84</b>, 1–5 (2011).<br/>[2] Ishiwata, S. <i>et al.</i> Emergent topological spin structures in the centrosymmetric cubic perovskite SrFeO₃, <i>Phys. Rev. B</i> <b>101</b>, 134406 (2020).<br/>[3] Mostovoy, M. Helicoidal ordering in iron perovskites, <i>Phys. Rev. Lett.</i> <b>94</b>, 137205 (2005).